The present invention relates to a new key and lock barrel for a lock set, which is simple to manufacture and assemble and which comprises one holder with one rotating body inside and one catching body posteriorly next to the rotating body, which rotating body comprises multiple washers and barrel plates, wherein the structure works by inserting the key into the rectangular spaces through the washers and barrel plates in a manner such that the turning of key aligns the notches on each washer and barrel plate so that the rotating body receives the catching body in the notches to open the lock; the good match of key and rotating body increases the precision of the mechanism of the present invention and reduces the possibility of error.